1. Field of the Invention
The present invention relates to an accelerator pedal module for vehicles.
2. Description of Related Art
Conventionally, an accelerator pedal module, which is mounted on a vehicle to control a driving state of the vehicle in accordance with a pressing amount of an accelerator pedal that is foot-actuated by a driver, is known (see WO2006/100133A1 corresponding to US2008/0184843A1, hereafter referred to as patent document 1, for example). In such an accelerator pedal module, a support member pivotably supports the accelerator pedal that is foot-actuated by a driver, and a spring biases the accelerator pedal in a reverse of a pedaling direction of the accelerator pedal. When a pedal force actuating the accelerator pedal is released, a biasing force of the spring returns the accelerator pedal to its initial position.
In the accelerator pedal module disclosed in patent documents 1, the biasing force of the spring is transmitted to a rotor that is located on a counter-pedal portion side end portion of the accelerator pedal, via a holder, a movement of which is guided by a guide portion. When a driver presses the accelerator pedal, the rotor pushes up the holder against the biasing force of the spring. At this moment, a rotation surface of the rotor moves around an arc about a rotation axis of the accelerator pedal, a position of a contact point of the rotor and the holder shifts, and the holder is inclined to the guide portion. The holder slides on the guide portion, being inclined to the guide portion. Therefore, the holder is worn with time on one side by a sliding movement on the guide portion, to cause jerkiness in a pedal power characteristic. As a result, a pedal operation feeling becomes worse. Therefore, in order to keep the pedal operation feeling good with time, it is desirable that the holder moves without being guided by the guide portion to prevent the holder from being worn on one side.
In this regard, JPH11-37335A, which is hereafter referred to as patent document 2, discloses a construction of a flow control valve, in which a spherical projection member that is supported by a straight cylindrical valve shaft is in contact with a spherical concavity member, and the spherical projection member straightly pushes up the spherical concavity member against a biasing force of a spring. In this flow control valve, a part of the spherical concavity member and a part of the spherical projection member that are in contact with each other have spherical surfaces. Further, a position at which the biasing force of the spring acts on the spherical concavity member is below a contact point of the spherical concavity member and the spherical projection member. Thereby, an orientation of the spherical concavity member is highly stable while the spherical projection member is moving to push the spherical concavity member. Therefore, the flow control valve disclosed in patent document 2 does not require a guide portion as disclosed in patent document 1, in order to guide a movement of the spherical concavity member. Therefore, the spherical concavity member is prevented from being worn on one side.
Thus, it is possible to eliminate the guide portion from the accelerator pedal module, by incorporating the above construction of the flow control valve into the accelerator pedal module, that is, by incorporating a construction of the spherical projection member into the rotor and a construction of the spherical concavity member into the holder, to locate a position at which the biasing force of the spring acts on the holder below a contact point of the holder and the rotor. However, in the accelerator pedal module, the rotation surface of the rotor moves around an arc, and the holder is pushed up against the biasing force of the spring to move along an arc when a driver presses the accelerator pedal. Therefore, a holder side end of the spring moves not along a straight path but along an arc while the spring is compressed. As a result, the operating efficiency of a spring falls, causing a problem to make the pedal operation feeling worse.